The present invention relates generally to the field of electrosurgery, and more particularly to surgical devices and methods which employ high frequency electrical energy to treat tissue in regions of the digestive tract and associated organs, such as the pharynx, esophagus, stomach, intestines, anorectum, liver, pancreas and the like. The present invention is particularly suited for treating the lower esophageal sphincter in patient""s suffering from gastroesophageal reflux.
Gastroesophageal reflux, better known as heartburn or acid indigestion, occurs when the esophageal mucosa suffers prolonged exposure to noxious gastric acid and pepsin because of deficiencies of the esophageal reflux barrier and acid-clearing mechanisms. Normally, the hydrocholoric acid and protease pepsin that are present in the stomach are excluded from the esophagus by the valve action of the lower esophageal sphincter (LES). Weakness of LES tone or abnormally frequent relaxations of the LES allow gastric acid and pepsin to reflux into the esophagus and potentially damage the mucosa. Symptoms of gastroesophageal reflux disease include heartburn, regurgitation, chest pain (due to a spasm of the acid-bathed esophagus), coughing, hoarseness, sore throat, gingivitis and asthma.
Treatment of gastroesophageal reflux typically involves pharmaceuticals that either neutralize acids in the stomach, or prevent the secretion of gastric acid into the stomach. Often, the complete control of heartburn requires extremely aggressive acid suppression. These pharmaceuticals, however, do not treat the problem (i.e., a loose lower sphincter). In addition, it has been shown that reflux can produce a broncho-contriction (asthma-like symptoms) either through reflex (vagally induced from reflux in the esophagus) or reflux into the trachea. Changing the ph of the stomach acid does not prevent these conditions.
A second pharmaceutical approach is to administer promotility agents that act to increase LES tone and, in some instances, improve esophageal acid clearance and accelerate gastric emptying. Bethanechol, a cholinergic agonist that enhances LES tone, was frequently used in the past. It is no longer widely employed, however, because of its poor efficacy, a high incidence of side effects, and a tendency to stimulate gastric acid secretion.
Esophageal strictures can be treated by forcible dilatation using flexible tapered bougies that are swallowed by the patient. Dilatation also can be performed by endoscopically using balloons. Although such dilatation is usually effective, strictures frequently recur if gastroesophageal reflux is not controlled.
The lower esophageal acid exclusion barrier can be restored by a surgical procedure in which the distal portion of esophagus is anchored in the abdomen by wrapping part of the fundus of the stomach around it. This procedure, called fundoplication, is intended to reestablish the normal anatomic relationships and reinforce the LES. Although fundoplication typically eliminates gastroesophageal reflux and affords complete resolution of symptoms, this procedure is extremely invasive, and often causes unwelcome side effects. After fundoplication surgery, for example, some patients are unable to belch and complain of frequent abdominal distention, a phenomenon known as gas-bloat syndrome. In addition, some patients who have good relief initially will develop recurrent reflux after a period of years.
The present invention provides systems, methods and apparatus for applying high frequency electrical energy to treat tissue in regions of the digestive system. The present invention is particularly suited for applying electrical energy to the lower esophageal sphincter to treat gastroesophageal reflux.
In one aspect of the invention, a method of the present invention comprises positioning an electrosurgical instrument adjacent a tissue structure of the lower sphincter so that one or more electrode terminal(s) are brought into at least partial contact or close proximity with the body structure. High frequency voltage is applied between the electrode terminal(s) and one or more return electrode(s) to elevate the temperature of collagen fibers within the tissue of the lower sphincter from body temperature (about 37xc2x0 C.) to a tissue temperature in the range of about 45xc2x0 C. to 90xc2x0 C., usually about 60xc2x0 C. to 70xc2x0 C. This temperature elevation substantially irreversibly contracts the collagen fibers within the tissue to tighten the lower sphincter and prevent or greatly reduce gastroesophageal reflux. The electrosurgical instrument may comprise a catheter that is advanced transluminally or through the patient""s mouth and esophagus down to the lower sphincter, or a more rigid probe that is introduced through a percutaneous or open penetration in the patient.
In a preferred embodiment, an electrically conducting fluid is provided between the electrode terminal(s) and one or more return electrode(s) positioned proximal to the electrode terminal(s) to provide a current flow path from the electrode terminal(s) away from the tissue to the return electrode(s). The current flow path may be generated by directing an electrically conducting fluid along a fluid path past the return electrode and to the target site, or by locating a viscous electrically conducting fluid, such as a gel, at the target site, and submersing the electrode terminal(s) and the return electrode(s) within the conductive gel. The collagen fibers may be heated either by passing the electric current through the tissue to a selected depth before the current returns to the return electrode(s) and/or by heating the electrically conducting fluid and generating a jet or plume of heated fluid, which is directed towards the target tissue. In the latter embodiment, the electric current may not pass into the tissue at all. In both embodiments, the heated fluid and/or the electric current elevates the temperature of the collagen sufficiently to cause hydrothermal shrinkage of the collagen fibers.
In another aspect of the invention, a sufficient high frequency voltage is applied between the electrode terminal(s) and one or more return electrode(s) to volumetrically remove at least a portion of the lower sphincter. Specifically, high frequency voltage is applied between the electrode terminal(s) and one or more return electrode(s) to remove a small tissue segment, channel or hole from the region near or in the lower sphincter to shrink the sphincter and prevent swelling, due to the formation of scar tissue as the wound heals. The high frequency voltage may be selected to effect a small amount of thermal damage to the walls of the channel or hole to facilitate the formation of scar tissue without extending this thermal damage beyond the immediate region of the target site The electrode terminal(s) may be translated relative to the lower sphincter during or after the application of electrical energy to sculpt a void within the lower sphincter, such as a hole, channel, stripe, crater, or the like. In some embodiments, the electrode terminal(s) are axially translated toward the lower sphincter to bore one or more channel(s) or hole(s) through a portion of the structure. In other embodiments, the electrode terminal(s) are translated across the lower sphincter to form one or more stripe(s) or channel(s). In most embodiments, electrically conducting fluid, such as isotonic saline, is located between the electrode terminal(s) and the tissue. In the bipolar modality, the conducting fluid generates a current flow path between the electrode terminal(s) and one or more return electrode(s). High frequency voltage is then applied between the electrode terminal(s) and the return electrode(s) through the current flow path created by the electrically conducting fluid.
In a specific configuration, the tissue is removed by molecular dissociation or disintegration processes. In these embodiments, the high frequency voltage applied to the electrode terminal(s) is sufficient to vaporize an electrically conductive fluid (e.g., gel or saline) between the electrode terminal(s) and the tissue. Within the vaporized fluid, a ionized plasma is formed and charged particles (e.g., electrons) are accelerated towards the tissue to cause the molecular breakdown or disintegration of several cell layers of the tissue. This molecular dissociation is accompanied by the volumetric removal of the tissue. The short range of the accelerated charged particles within the tissue confines the molecular dissociation process to the tissue surface layer to minimize damage and necrosis to the underlying tissue. This process can be precisely controlled to effect the volumetric removal of tissue as thin as 10 to 150 microns with minimal heating of, or damage to, surrounding or underlying tissue structures. A more complete description of this phenomena is described in commonly assigned U.S. Pat. No. 5,683,366, previously incorporated herein by reference.
Apparatus according to the present invention generally include an electrosurgical probe or catheter having a shaft with proximal and distal ends, one or more electrode terminal(s) at the distal end and one or more connectors coupling the electrode terminal(s) to a high frequency power supply. The apparatus will further include one or more return electrode(s) either located on an outer surface of the patient, or on the probe shaft or another instrument. The high frequency power supply is configured to apply a voltage difference between electrode terminal(s) and the return electrode(s) that is sufficient to effect contraction of collagen fibers within the tissue structure to stiffen the lower sphincter.
The apparatus will preferably further include a fluid delivery element for delivering electrically conducting fluid to the electrode terminal(s) and the target site. The fluid delivery element may be located on the instrument, e.g., a fluid lumen or tube, or it may be part of a separate instrument. Alternatively, an electrically conducting gel or spray, such as a saline electrolyte or other conductive gel, may be applied the target site. In this embodiment, the apparatus may not have a fluid delivery element. In both embodiments, the electrically conducting fluid will preferably generate a current flow path between the electrode terminal(s) and one or more return electrode(s). In an exemplary embodiment, the return electrode is located on the instrument and spaced a sufficient distance from the electrode terminal(s) to substantially avoid or minimize current shorting therebetween and to shield the return electrode from tissue at the target site.
In a specific configuration, the electrosurgical instrument comprises a catheter designed for advancement through the patient""s mouth, down the esophagus into the region of the lower sphincter. In this embodiment, the catheter may optionally include an endoscope, or the system may include a separate endoscope. The catheter shaft will include an electrically insulating electrode support member having a tissue treatment surface at the distal end of the shaft. One or more electrode terminal(s) are coupled to, or integral with, the electrode support member such that the electrode terminal(s) are spaced from the return electrode. In one embodiment, the catheter includes an electrode array having a plurality of electrically isolated electrode terminals embedded into the electrode support member such that the electrode terminals extend about 0.0 mm to about 10 mm. In this embodiment, the catheter will further include one or more lumens for delivering electrically conductive fluid to one or more openings around the tissue treatment surface of the electrode support member. In an exemplary embodiment, the lumen will extend through a fluid tube exterior to the catheter shaft that ends proximal to the return electrode.
The system may optionally include a temperature controller coupled to one or more temperature sensors at or near the distal end of the instrument. The controller adjusts the output voltage of the power supply in response to a temperature set point and the measured temperature value. The temperature sensor may be, for example, a thermocouple, located in the insulating support that measures a temperature at the distal end of the instrument. In this embodiment, the temperature set point will preferably be one that corresponds to a surface temperature of tissue that results in the contraction of the collagen within the underlying tissue, i.e., about 60xc2x0 C. to 70xc2x0 C. Alternatively, the temperature sensor may directly measure the tissue temperature (e.g., infrared sensor). This embodiment is advantageous in situations when the surgeon is moving the instrument transversely across the tissue.